TLDR; Their mistake was building a gigantic house, based on emerging sustainable-energy tech, whilst in their 70s. Any two of these things might have been reas

TLDR; Their mistake was building a gigantic house, based on emerging sustainable-energy tech, whilst in their 70s. Any two of these things might have been reasonable, though I feel that the sheer size of the house is ultimately the problem - it's going to be a lot of work to maintain a house on this scale in the best of circumstances.